Staff-FTP is a unique ftp client that is easy to use. Unlike others it comes with full tls/ssl support (also with FXP). It also includes a glftpd-manager with all the site commands (drftpd and other command sets as well).
This is not only a ftp program but it also supports FXP which is a way to quickly transfer data from one server to another without the limit of your bandwidth.
Custom FTP-Commands
Each FTP server supports different custom commands which can be very helpful for you. The software will show you everything in a nice interface.